In a message dated 4/11/2008 12:24:20 P.M. Pacific Daylight Time, [EMAIL PROTECTED] writes:
> "Wacom Products Modified RG-214 Double shielded" on it, it > is an untinned double shielded cable Are the shields the same exact material makeup... or is one copper and the other something else? They are both copper. > which will provide the necessary isolation although there > is a large segment of the forum participants that feel that > untinned double shielded cable is vulnerable to low level noise ....not the untinned part... the part with dissimilar shield materials is the problem generator. In short vulnerable no, possible PIM generator yes. You're preaching to the choir. I think untinned double shielded copper is very adequate to duplexer connections. But there are contributors aboard who feel that silver plated shields are a better choice. > The Type N terminated interconnects on the 642 duplexer > supplied by Wacom for 145.29/144.69 were 12.5 inches including > the connectors, tip to tip. I've actually seen that duplexer... :-) the receive leg would be longer if you could knats behind it on really good test equipment. I have a near duplicate duplexer on 145.470 and the rx leg is about 1/4 inch longer than the tx cable length. Hey you, get your cottin pickin hands outta that cabinet! I queried Lloyd Alcorn regarding this in the 80s and he indicated that he was hard pressed to improve the tracker curves using different TX and RX cables on a 600KC VHF split. The cables supplied for the sets he supplied me all had identical 12.5 inch length cables. > The optimum length for cables terminated with UHF connectors > might be slightly different because the UHF connectors and > chassis jacks are probably not a true 50 ohms at VHF frequencies. Depends on who spec'd and made the UHF Connectors. I know a group of Certified (looney) RF Engineers who say UHF Connectors are a train wreck and another (also looney) Engineering group who have spec'd them on serious lab test gear for operation well past 500 MHz with no real impedance bumps. Go figure... That's interesting. Perhaps both loony groups are correct. You can't do much about an impedance mismatch between a connector and an associated cable because the cable has a fixed nominal impedance. But the chassis connector impedance mismatch can be accounted for by the network that feeds it. Didn't Motorola use UHF connectors on their equipment for decades and their position was that the impedance mismatch was accounted for. I remember Hank Edwards at Phelps Dodge commenting that when they designed their sticks, they accounted for UHF cable and chassis connector mismatches in the antenna design itself. K7IJ **************It's Tax Time! Get tips, forms and advice on AOL Money & Finance. (http://money.aol.com/tax?NCID=aolcmp00300000002850)
